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What is a Vector Database?

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[In a vector database] Data points are stored as arrays of numbers called “vectors,” which are clustered based on similarity. This design enables low-latency queries, making it ideal for AI applications.
Jim Holdsworth & Matthew Kosinski/ Enterprise Technology Writers
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Visualizing how similar vectors are stored and searched

Vector databases store and search data using vectors — numerical representations of things like text, images, or audio. These databases are designed to find similar items based on meaning, not just exact matches.

Let’s say you searched for “best places to visit in summer.” A traditional database might look for exact text matches. But a vector database looks for entries semantically similar to your query, even if they use totally different words — like “top vacation destinations for warm weather.”

Why does this matter? It’s the backbone of Retrieval-Augmented Generation (RAG) systems, which feed relevant context into language models like ChatGPT. When you ask a question, the system:

  1. Turns your query into a vector
  2. Searches the vector database for similar content
  3. Feeds that content into the model so it can respond with grounded answers

Key Features:

  • Finds similar items using cosine or Euclidean distance
  • Handles high-dimensional vectors from models like OpenAI, Cohere, or Hugging Face
  • Extremely fast at scale with billions of entries

Real-World Use Cases:

  • Powering AI search (like in Notion AI or ChatGPT plugins)
  • Personalized recommendations (e.g., similar songs, movies, products)
  • RAG pipelines for grounding LLM responses

It’s like Google Search — but for meaning, not just words.

FAQ

What is a vector database?
A database that stores and retrieves data using vectors — numerical representations of things like text or images — to find similar content based on meaning.
How does a vector database work?
It turns content into vectors, then compares those vectors using mathematical distance (like cosine similarity) to find the closest matches.
Why are vector databases important in AI?
They’re essential for RAG systems, powering AI assistants by giving them access to relevant context from knowledge bases.
What tools use vector databases?
Tools like ChatGPT (with RAG), Notion AI, and search platforms like Pinecone, Weaviate, and FAISS use vector databases to enable smarter search and grounding.

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